JPH07105168B2 - Flat cable and manufacturing method thereof - Google Patents

Description

The present invention relates to a flat cable and a manufacturing method thereof.

"Prior art" A flat multi-core cable is used as an electric wire for internal wiring of video equipment, audio equipment, OA equipment, computer equipment, and the like. Among the flat cables, polyvinyl chloride is used as an insulator that sandwiches the conductor, and the flat cable is inexpensive, and the manufacturing process is completed only by thermocompression bonding the polyvinyl chloride sheet and the conductor, so no adhesive is required. And is the most widely used flat cable today.

On the other hand, as the range of use and applications of flat cables expands, engineering such as polyester resin is considered especially in terms of mechanical properties of insulators, dimensional accuracy, heat resistance of insulating sheet and adhesive, and chemical resistance. There is a need to use plastics as insulating sheets.

In such a case, for example, when a biaxially stretched polyester film is used as the insulating sheet, the conductor and the biaxially stretched polyester film cannot be bonded by a thermocompression bonding method as in the case of polyvinyl chloride, Usually, some kind of adhesive is interposed between the conductor and the biaxially stretched polyester film, and the biaxially stretched polyester film and the conductor are bonded by thermocompression bonding.

As the adhesive between the biaxially stretched polyester film and the conductor, a two-component thermosetting polyester adhesive is often used, and the adhesive has good heat resistance and chemical resistance.

However, in the case of a two-component adhesive, there is a problem that the curing of the adhesive requires a high-temperature and long-time heat curing process, and there is a problem that the manufacturing process cannot be continued. There are cases where it becomes a problem. Further, in order to obtain sufficient peel strength between the insulating sheet and the conductor, for example, a chemical pretreatment of coating the insulating sheet with a primer component may be necessary.

On the other hand, a hot-melt resin adhesive is known as an adhesive that can be used as an adhesive between a biaxially stretched polyester film and a conductor. The hot melt resin adhesive is a solid adhesive which is based on a thermoplastic resin and which is mixed with a plasticizer, a tackifier, an antioxidant and the like as required. The hot-melt resin adhesive is used by applying it to a carrier and thermocompression-bonding it, but since the hot-melt resin adhesive is solidified by cooling, it has an advantage that bonding can be completed in an instant.

For hot-melt resin adhesives, ethylene, vinyl acetate,
Polyolefin resin such as maleic anhydride copolymer, ethylene / ethyl acrylate / maleic anhydride copolymer, saturated polyester resin, polyamide resin,
Thermoplastic rubbers such as butyl rubber and styrene block polymers are known.

If this hot melt resin adhesive is used as an adhesive between the insulating sheet and the conductor, an instantaneous adhesive between the insulating sheet and the conductor is possible.

However, a flat cable using a hot-melt resin adhesive as an adhesive between an insulating sheet and a conductor has a problem in heat resistance because the hot-melt resin adhesive is thermoplastic, and further, for example, trichloroethane. There is also a problem that the chemical resistance to a chlorine-containing organic solvent is inferior to that of the two-pack type thermosetting polyester adhesive mentioned above.

"Problems to be solved by the invention" As described above, engineering plastics such as biaxially stretched polyester films have recently been developed from the viewpoint of mechanical properties of insulators, heat resistance, chemical resistance and the like. There is a need for flat cables used as conductor insulation.

However, in such a case, the conductor and the insulator cannot be bonded by the thermocompression bonding method such as a method for manufacturing a polyvinyl chloride-insulated flat cable, and it is usually necessary to interpose an adhesive.

For example, when a biaxially stretched polyester film is used as an insulating sheet, a two-component thermosetting polyester adhesive is generally used as an adhesive in general, but it takes a long time at high temperature for curing. , It may hinder the continuous production of flat cables, or the pot life of the adhesive may become a problem.

On the other hand, if a hot-melt resin adhesive is used, instantaneous adhesion is possible, so continuous production of flat cables is possible, but the heat resistance and chemical resistance of the adhesive may be a problem. .

Due to the above reasons, in a flat cable using engineering plastics such as biaxially stretched polyester film as the insulator of the conductor, it is possible to instantaneously bond the conductor and the insulator, and the heat resistance of the adhesive It has been desired to develop a flat cable and a manufacturing method for the flat cable, which does not cause a problem in the durability and chemical resistance.

In view of the above, the present invention is a flat cable and a method of manufacturing the flat cable developed to solve such problems.

“Means for Solving the Problems” That is, the flat cable of the present invention is mainly composed of a hot-melt resin and a polyfunctional compound having a plurality of unsaturated bond components in a molecule between insulating sheets made of a polymer material. A flat cable in which an adhesive layer is provided and a conductor is arranged in the adhesive layer between the insulating sheets, wherein the insulating sheet and the adhesive layer or the adhesive layer is irradiated with ionizing radiation. To do.

Further, the flat cable manufacturing method of the present invention is a flat cable manufacturing method in which an adhesive layer is provided between insulating sheets made of a polymer material, and a conductor is arranged in the adhesive layer between the insulating sheets. The hot-melt resin and an adhesive mainly composed of a polyfunctional compound having a plurality of unsaturated bonds in the molecule are interposed between the insulating sheet and the conductor, and a conductor is inserted between the adhesive and the thermo-compression roll. The method is characterized by including a step of continuously adhering and a step of irradiating ionizing radiation after the thermocompression bonding roll.

The embodiments of the flat cable and the manufacturing method thereof according to the present invention include at least the following.

A resin component mainly composed of a saturated copolyester of the hot-melt resin component of the adhesive layer or a resin component mainly composed of an ethylene / ethyl acrylate copolymer grafted with an alkoxysilane.

The present invention will be described in detail below.

As a result of diligent study on the above problems, the present inventor has found that (1) as shown in FIG. 1, a plurality of hot-melt resins and a plurality of molecules are included in the molecule between insulating sheets (2) and (2) made of a polymer material. A flat cable in which an adhesive layer (3) mainly comprising a polyfunctional compound having an unsaturated bond content of (1) is provided, and the conductor (1) is arranged in the adhesive layer between the insulating sheets,
A flat cable in which the insulating sheet and the adhesive layer or the adhesive layer has a cross-linked structure by irradiation of ionizing radiation has excellent heat resistance and chemical resistance, and as a manufacturing method thereof, (2) as shown in FIG. In addition, an adhesive sheet (3) mainly composed of a hot-melt resin and a polyfunctional compound having a plurality of unsaturated bond components in the molecule is interposed between insulating sheets (2) and (2) made of a polymer material. Then, the conductor (1) is inserted between the insulating sheet and the adhesive sheet, and these thermocompression-bonding rolls (4) and (4) are continuously brought into close contact with each other, followed by irradiation with ionizing radiation (5) (for example, It is possible to continuously produce a flat cable having excellent heat resistance and chemical resistance by adopting the method from the upper side, the lower side, or the upper and lower sides. Hot melt resin is saturated Not only heat resistance and chemical resistance, but also the degree of adhesion between the conductor and the insulation sheet, if it is a resin component mainly composed of polyester or a resin component mainly composed of ethylene / ethyl acrylate copolymer grafted with alkoxysilane However, they have found that a flat cable having extremely excellent adhesion strength can be obtained without using a method such as coating with a primer component, and have completed the present invention.

"Function" As a method for forming the adhesive layer, coating on the insulating sheet or melt extrusion method can be applied. In particular, the adhesive is a resin component mainly composed of saturated polyethylene, or an ethylene / ethyl acrylate grafted with an alkoxysilane. When a resin composition in which a polyfunctional compound having a plurality of unsaturated bond components in the molecule is added to a resin component mainly composed of a copolymer is used, the melt extrusion method may be used in the range of 10 to 100 μm. The adhesive layer can be continuously formed with a film thickness of. Furthermore, in this case, the thermocompression bonding between the insulation sheet and the conductor is 120 at the roll temperature.
Can be set in the range of ~ 200 ℃, for example, when using a biaxially stretched polyester film or polyimide film as the insulating sheet, the range of 150 ~ 180 ℃ to obtain sufficient peel strength between the conductor and the insulating sheet. Was within the desired range.

Further, it goes without saying that a physical surface treatment such as corona discharge treatment (improvement of wettability of the insulating sheet with respect to the adhesive) may be performed on the insulating sheet before the hot roll pressure bonding.

Regarding the irradiation of ionizing radiation that is performed after the heat roll pressure bonding, it is possible to use α rays, electron rays (β rays), γ rays, ultraviolet rays, X-rays, etc. From an industrial point of view such as irradiation time, it is particularly preferable to use an electron beam. In that case, in terms of the transmission thickness, the acceleration voltage of the electron beam is preferably in the range of 200 kV to 1 MV,
The irradiation dose may be appropriately set within the range of 3 to 25 Mrad.

The saturated copolyester resin referred to in the present invention, polyethylene terephthalate sebacate, polybutylene terephthalate sebacate, polybutylene terephthalate adipate, polyethylene terephthalate isophthalate, and the like can be mentioned as a specific example, further copolyester resin. The ethylene / ethyl acrylate copolymer grafted with an alkoxysilane is, for example, γ-methacryloxypropyltriethoxysilane in the presence of a radical polymerization catalyst such as t-butylperoxybenzoate on an ethylene / ethyl acrylate copolymer. Specific examples include a graft copolymer obtained by hot-melt grafting an alkoxysilane such as in a uniaxial or multiaxial mixer. The chill acrylate content, 1
-30% by weight, and the amount of graft silane can be 0.01 to 0.3% by weight.

Further, as the polyfunctional compound having a plurality of unsaturated bond components in the molecule, ethylene glycol diacrylate,
Acrylic monomers such as trimethylolpropane trimethacrylate and pentaerythritol triacrylate, as well as acrylic monomers such as triallyl cyanurate, triallyl cyanurate and dietrene glycol diallyl ether, acrylic modified epoxy Oligomer, acrylic modified ester oligomer, acrylic modified urethane oligomer, acrylic modified spiro acetal oligomer, acrylic modified oligomers such as acrylic modified butadiene oligomer, and oligomers such as polyene-thiol type spiro acetal oligomer can be mentioned. It is possible to select the polyfunctional compound species and the blending amount, and to mix the two, an open roll mixer or a single-screw or multi-screw mixer can be used. If necessary, a tackifier, an antioxidant and the like may be added to the resin composition used in the present invention. "Example" The present invention will be described with reference to the following examples. As a concrete example, thickness
When a 50 μm biaxially stretched polyester film is used as an insulating sheet and a tin-plated flat conductor with a thickness of 35 μm and a width of 2.54 mm is used as a conductor, a saturated polyester resin (softening point: 115 ° C., glass Transition point 9 ℃,
Melt viscosity at 200 ° C 2800 poise, 90 parts by weight of Toray Co., Ltd., bifunctional acrylic modified ester oligomer (bifunctional oligoester acrylate, room temperature viscosity 3 poise,
An adhesive sheet obtained by melt-extruding a resin composition containing 10 parts by weight of Toa Gosei Chemical Industry Co., Ltd. to a thickness of 30 μm can be used. In this case, insulation is performed at a roll temperature of 150 ° C. and a linear velocity of 3 m / min. When the sheet and the conductor were thermocompression bonded, a flat cable was continuously obtained. As a result of irradiating this flat cable with an electron beam of 400 kV for 15 Mrad, the peel strength between the insulating sheet and the conductor was 1.30 Kg / cm.

Put this flat cable in trichloroethane at room temperature.
As a result of examining the peel strength between the conductor and the insulating sheet before and after immersion for a time, it shows a peel strength of 1.22 Kg / cm after immersion,
The peel strength hardly changed before and after the immersion.

On the other hand, it was found that the flat cable before electron beam irradiation had its peel strength reduced to 0.36 Kg / cm when immersed in trichloroethane at room temperature for 1 hour.

Furthermore, the insulating sheet was removed from the end of this flat cable by a length of 10 mm to expose the conductor, and 5 mm at the tip of the exposed conductor was immersed in a solder bath at 260 ° C for 5 seconds to examine the solder heat resistance of the adhesive layer. . As a result, in the sample irradiated with the electron beam, no outflow or foaming of the adhesive layer of the insulating sheet terminal portion was observed, whereas in the sample not irradiated, it was observed that the adhesive layer of the insulating sheet terminal portion flowed out. A fine foaming phenomenon was observed.

It should be noted that various examples of the present invention are shown in Tables 1 and 2 in comparison with the comparative examples, and the examples of the present invention have heat resistance and chemical resistance as compared with those of the comparative examples. Is excellent.

"Effects of the Invention" As described above, according to the present invention, it is possible to carry out the production of a flat cable using engineering plastics such as biaxially stretched polyester film as an insulator in a continuous process, and further, chemical resistance, Since a flat cable having excellent heat resistance can be obtained, its utility value in the field of application of the flat cable is very large.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a flat cable of the present invention, and FIG. 2 is a perspective view illustrating a method of manufacturing a flat cable of the present invention. (1) ... Conductor, (2) ... Insulating sheet, (3) ... Adhesive layer, (4) ... Crimping roll, (5) ... Ionizing radiation

Claims (4)

[Claims] 1. An adhesive layer mainly composed of a hot-melt resin and a polyfunctional compound having a plurality of unsaturated bond components in the molecule is provided between insulating sheets made of a polymer material, and the insulating sheets are provided between the insulating sheets. A flat cable having a conductor arranged in an adhesive layer, wherein the insulating sheet and the adhesive layer or the adhesive layer is irradiated with ionizing radiation. 2. The hot melt resin component of the adhesive layer is a resin component mainly composed of a saturated copolymerized polyester or a resin component mainly composed of an alkoxysilane-grafted ethylene / ethyl acrylate copolymer. The flat cable described in (1). 3. A method of manufacturing a flat cable in which an adhesive layer is provided between insulating sheets made of a polymer material, and a conductor is arranged in the adhesive layer between the insulating sheets is a method for producing a flat cable. A step of interposing an adhesive mainly composed of a polyfunctional compound having a plurality of unsaturated bond components, inserting a conductor between the insulating sheet and the adhesive, and continuously adhering these with a thermocompression bonding roll And a step of irradiating with ionizing radiation after the thermocompression-bonding roll. 4. The hot melt resin component of the adhesive layer is a resin component mainly composed of a saturated copolyester or a resin component mainly composed of an alkoxysilane-grafted ethylene / ethyl acrylate copolymer. (3) The method for producing a flat cable according to item 3.